|
Equation
of time and length of solar day
The
Equation
of Time
is the difference between the time determined by a sundial
and the clock time. It is due to the obliquity of the
Earth's axis and the unequal motion of the Earth around the
Sun (ellipse). The value, computed for 12:00 UT, is between
-14 :20 min (near Feb 12) and +16:24 min (near Nov
4).
The
length
of the current solar day
(i.e. the time interval between culmination of the Sun on
prev. and curent day) is not exactly 24 hours; the
difference is given in brackets (e.g. +18.8 s).
For
2001:
|
|
equation
of time
|
length
of solar day
|
|
Jan
1
|
-
03:45 min
|
24
h - 28.3 s
|
|
15
|
-
09:34 min
|
24
h - 21.2 s
|
|
Feb
1
|
-
13:38 min
|
24
h - 08.1 s
|
|
15
|
-
14:07 min
|
24
h + 02.8 s
|
|
Mar
1
|
-
12:18 min
|
24
h + 11.6 s
|
|
15
|
-
08:51 min
|
24
h + 16.8 s
|
|
Apr
1
|
-
03:48 min
|
24
h + 17.9 s
|
|
15
|
+
00:02 min
|
24
h + 14.6 s
|
|
May
1
|
+
02:57 min
|
24
h + 07.3 s
|
|
15
|
+
03:40 min
|
24
h - 00.6 s
|
|
Jun
1
|
+
02:09 min
|
24
h - 09.1 s
|
|
15
|
-
00:31 min
|
24
h - 12.8 s
|
|
Jul
1
|
-
03:53 min
|
24
h - 11.6 s
|
|
15
|
-
05:59 min
|
24
h - 06.2 s
|
|
Aug
1
|
-
06:18 min
|
24
h + 03.6 s
|
|
15
|
-
04:24 min
|
24
h + 11.7 s
|
|
Sep
1
|
+
00:06 min
|
24
h + 18.9 s
|
|
15
|
+
04:55 min
|
24
h + 21.4 s
|
|
Oct
1
|
+
10:26 min
|
24
h + 19.4 s
|
|
15
|
+
14:17 min
|
24
h + 13.4 s
|
|
Nov
1
|
+
16:24 min
|
24
h + 01.7 s
|
|
15
|
+
15:20 min
|
24
h - 10.0 s
|
|
Dec
1
|
+
10:50 min
|
24
h - 22.3 s
|
|
15
|
+
04:41 min
|
24
h - 28.8 s
|
|